1. Field of the Invention
The present invention relates to the use of mono- and bis(methylbenzyl)xylene isomers as heat transfer fluids.
2. Description of the Prior Art
The principle of heat exchange by means of fluids other than water is described in Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd Edition, Vol. 12, pages 171-190. It describes the use of mineral or synthetic oils having a boiling point, under atmospheric pressure, ranging from 200.degree. to 400.degree. C. The heat transfer may be carried out under atmospheric pressure, or under a few bars of pressure, instead of the very high water vapor pressure at the same temperature.
The use of dibenzyltoluene and bis(methylbenzyl)toluene as a heat transfer medium is described in U.S. Pat. No. 3,475,115. However, bis(methylbenzyl)toluene is solid at -17.degree. C. and its viscosity at 20.degree. C. is 204 centistokes. With respect to dibenzyltoluene, its pour point is -34.degree. C. and its viscosity at 20.degree. C. is 35 centistokes.